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AGN天体的主要特征之一,就是它们的光谱中有宽而强的发射线,因此,这些宽发射线的产生区域BLR为人们提供了一个了解AGN天体物理本质的独特而重要的场。在文中围绕讨论了BLR基本物理特征,评述近年来有关的理论和观测研究进展及其现状在文(Ⅱ)中主要涉及BLR的几何结构和尺度及其运动学研究的进展和现状。 相似文献
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以大鹏半岛国家地质公园为调查对象,通过野外重点地质路线观察测制火山地层剖面,结合卫星遥感图像解译,进行锆石同位素激光定年测试及微量元素LA-ICP-MS分析、火山岩石显微镜薄片鉴定、岩石主量元素分析和微量元素ICP-MS分析,结果发现:该区火山活动的分带明显受区域性北东向及北西向断裂构造所控制,公园内中生代火山岩相基本为陆相喷发,岩石基本分为酸性及中酸性两类,多属钙碱性岩,部分为弱碱性岩。新发现七娘山火山穹丘、三角山-大燕顶火山穹丘,雷公打石山峰、鸡公秃等12处火山锥,摇摆石等6个火山柱及鸡公秃火山锥南西侧的火山针,大燕顶古火山口等火山机构。特征火山岩方面,有隐爆火山集块(角砾)岩、崩积火山集块岩、基浪堆积层-"火山-沉积碎屑岩"。公园内古火山地貌景观有一级地貌景观点3处、二级5处、三级7处。认为该区中生代以来,至少经历过3期5次火山喷发活动,反映了库拉-太平洋板块与欧亚大陆板块相互作用的动力过程及我国东南沿海浙闽粤港巨型火山活动带的部分特征,是亚洲大陆边缘大规模火山喷发(岩)带侏罗纪-白垩纪火山岩系较有代表性的地段,是研究我国东南沿海侏罗纪-白垩纪火山活动的天然博物馆。 相似文献
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三江地区重力场特征和岩石圈构造 总被引:2,自引:0,他引:2
蒋福珍 《武汉大学学报(信息科学版)》2002,27(2):122-126
利用重力、地震层析成像等多种资料 ,并利用场分离、正反演以及阻尼最小二乘法、约束最小二乘法等数学方法 ,对重力异常进行分离 ,用地震层析成像的结果作为约束进行反演 ,得到地壳上地幔不同深度的密度分布和莫霍面深度等结果。 相似文献
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ABSTRACTThe aim of this study is to reveal statistical characteristics and exceedance probability of discharge under the combined effect of climate change and human activities. The study is conducted in the Xiaoqing River in Jinan, China, based on data of discharge, land-use types and precipitation from the period 1970–2016. A multivariate joint probability distribution of the data is established to test the univariable, bivariable and trivariable change points. These are then used to calculate and analyse the risk probability of discharge exceeding the specific values under different conditions of precipitation and land-use type. The results show that the change point calculated by trivariate joint distribution can reduce the disturbance of the change point obtained with the univariable or bivariable approach and reflect the changes of various factors in the hydrological processes more objectively. When the land-use type is taken into consideration, the trivariate distribution can reflect the variation of hydrological processes more reasonably. 相似文献
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A study was conducted to evaluate the effects of meat and bone meal (MBM) and poultry by-product meal (PBM) as the replacement
of fish meal in the diets on the growth performance, survival and apparent digestibility coefficients (ADC) of Litopenaeus vannamei. The basal diets were formulated with 22% fish meal and other ingredients which provided about 40% protein and 9% lipid in
the diet. The experimental diets included MBM or PBM to replace 0, 20%, 40%, 60% and 80% of total fish meal respectively.
All diets were iso-nitrogenous and isocaloric in gross terms. The results showed that there were no significant differences
(Pτ;0.05) in growth performance and ADC among the treatments fed with the diets in which 0–60% fish meal had been replaced with
MBM, while the percent weight gain (WG, %), body length gain (BLG, %) and ADC significantly decreased when the MBM was up
to 80% of the fish meal. There were no significant differences (Pτ;0.05) in growth performance and ADC among all the treatments fed with the diets in which 0–80% fish meal had been replaced
with PBM. 相似文献
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边缘撕裂--一种致裂致震机制 总被引:1,自引:1,他引:0
明确提出两个板块或地块之间相互作用(主要是错动)中存在一种致裂致震机制-边缘撕裂,并以中国云南境内的红河断裂和美国加州的圣安德列斯两侧地块的边缘撕裂现象为例作了具体阐述。 相似文献
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